Improvement in protracting trigonometers



1. WMM. Pr`otracting Trigunume'ters.

Patented Ap`ri|14,1874.

UNITED @STATES PATENT OFFICE.

JosIAH LYMAN, or LENox, MASSACHUSETTS.

IMPIRVEMENT IN PROTRACTING TRIGONOMETERS.

i Specification forming part of Leiters Patent No. 149,590, dated April14. 1874; application filed December 5, 1872.

To all whom it may conce-rn:

Beit known that I, JosIArr LYMAN, of Lenox, in the county of Berkshire,in the State of Massachusetts, have invented a new and ImprovedDrafting-Instrument, which I call Improvedv Protracting Trigonometer;and I do hereby declare that the f'ollowing is a full and exactdescription thereof, reference beinghad to the accompanying drawings'andto the letters of reference marked thereon.

My invention consists, first, in the substitution of a sliding graduatedarc in the trigonometer instead ofthe same fixed, and so arranged thatitmay be instantly shifted fortyfive degrees, or less, to right or left,at the pleasure of theoperator, thus enabling him to make any side ofhis drawing which he may find the most convenient, either parallel `orat right angles with his drafting-board; secondly, in so connecting,with the arm of the protractor, a sliding T that it shall both take theplace of the end borders of the board, and enable hiln who uses it tolay down upon paper two distances at right angles to each other at thesame time without changing the instrument, and at any desired angle;thirdly, in

such an attachment of the .arms .of both .the

protractor and of the sliding T that each is susceptible of niceadjustment, including the peculiar manner of adjustment.

To enable others skilled in the art to comprehend and usemy invention Iwill describe in detail its construction, manner. of working, andapplications. i

Figure llpresentsia birds-eye View of the instrument on a Scale ofone-half linear size, and in exact proportions, except that theprotractor and T-arlns are represented as broken oii for lack of space.All the other figures are of full and exact Size. Fig. 2 is alongitudinal section of the base, with its frame, plates, pivots, nuts,graduated arc, Vernier, Sto., and Fig. 8 the same section of the slidingT in its normal position on the protractorarm, except that, by mistake,it is drawn inverted. Fig 3 represents the Vernier-plate, separate fromthe instrument, with its several orifices. Fig. 4 shows the attached endof the protractor-arm, also separate from the instrument, with thepivot-orice P and two adjusting-orifices, A A, all being beveled to anangle of forty-iiveI degrees. Fig. 5 is avtransverse section oftheprotractor-limb,including the frame, the graduated arc, and clamp forthe same, at the dotted lines l d, Fig. 1. Fig.

' 6 is a section of the central part ofthe T-head at, the dotted line d,showing the manner of adjusting, at exactly right angles, the T-arrn T Aby the action of lthe adjusting-nuts A N A N against the two tongues ofsaid arm T T', the tongue T of said head having a pivoted attachment tothe T-arm by means of the pivot-nut T vP N, Figs. l and 8. Fig. 7 is atransverse section of the 4protractor-arm at the dotted line d', showingthe vernier-plate V P, protractor-arm P A, screws Sc Se, which arepermanently attached to the former, and the adjusting-nuts A N A` N,showing the manner in which they act againstthel outer side of thebeveled adiusting-orifices A A, Figs. l and 4, of the protractor-arm.This adjustment is, in all respects, similar to that shown in Fig.r 6;and its object is to bring the protractor-arm. nicely at right angleswith the face of the base when its Vernier is set at O. Fig. 8 is alongitudinal section of the T through its central line, drawn'by mistakein ,an inverted position. Fig. `9 presents, at full size, that portionof the T adjacent to the spring for the purpose of showing its shape andbearing, the ton gnes above it being represented as cnt away for .thisobject.

The protractor frame or base l? F, Figs. l, 2, is a plate of brass orGerman silver about one-seventh of an inch thick. Sl is a circular slotin the frame, of one hundred and eighty Vdegrees length, extendingninety degrees to the right and left of the 0 or central point. In thisslot slides the depressed part of the graduated limb or circle C, beingnicely tted thereto. This part, depressed by half the thickness of theframe, as seen in Fig. 2, isa littlel less than ninety degrees long 5and near its vtwo extremities are permanently inserted the twoclamp-screws, throughwhich the dotted lines d d, Fig. l, pass, clearlyShown in Fig. 5. Hence, when the graduated arc is unclamped it may beslid either to the right or left forty-five degrees, or any amount lesswhich the operation on hand may require. This facility renders theinstrument far more convenent and extended in its applications, withresults more reliable and a great saving of time. D is a circulardepression in the central part of the frame, of half its thickness, V P,Fig. 2, for the playing of the vernierplate. Into an orifice in itscenter, as seen in the same figure, is soldered the socket-piece S P forreceiving the main pivot M P, the fornier being made of brass and thelatter of bronze, or vice versa, nicely fitted to each other. TheVernier-plate V P, Figs. 2, 3, consists of aplate of soft steel aboutone-fourteenth of an inch thick, Fig. 2, of the length, breadth, andshape shown in Fig. 3. To this is attached, by means of the iixed nut FN, the Vernier V, Figs. 1, 2, made of German silver, of the length,breadth, form, and thickness shown in the latter figures.. Thisattachment is further secured by means of the fixed nut F N, Figs. 1, 2,3, which is screwed into the Vernier-plate, formi-ng also an internalscrew for the main clamp-screw M C S, Fig. 2. The addition of theclamp-piece C P, corresponding in shape laterallyr with the vernier,which lies directly above it, but extending farther toward the mainpivot, completes the clamp. Into the orifices P A A, Fig. 3, arepermanently inserted iron or steel screws for receiving the -pivot-nut PN, Fig. 2, and two adjusting-nuts at A A, Figs. 1 and 4, in all respectslike A N A N, Fig. 6. The socket of the Vernier-plate Soc, Fig. 3, isnicely fitted to the main pivot M P, Fig. 2; and these, with theprotractor-frame, are all held in their normal position by means of thenut N, Figs. 1, 2. The protractor-arm P A, Figs. 1, 2, 4, consists of asteel plate, with saw temper, about one-fourteenth of an inch thick, oneand onehalf inch wide, and of two feet length, more or less, accordingto the speciiic use of the instrument. It is attached to theVernierplate by means of the pivot-nut and two adjusting-nuts, referredto above, the adjustingorifices A A being placed, for the purpose ofadjustment, about one-iiftieth of an inch nearer together than thecorresponding screws in the Vernier-plate at A A, Fig. 3. By thisarrangement, in the first place, the arm may be instantly removed andexchanged for another of different length; and, secondly, it can bereadily and with great nicety adjusted with an accompanying wrench.precise arrangement and operation of the adjusting-nuts, those of theprotractor-arm and of the T-arm being identical in principle, thoughdifferent in form. Figs. 1, 6, 8, 9 show the precise construction andarrangement of Fig. 7 shows thel .A N A N. The T-head and arm are madeof soft steel, of the same thickness with the protractor-arm; and thehead is held in constant and close contact with the latter arm by meansof the spring S. The T is easily reversed,

and, in bringing it into position on either side of the protractor-arm,the thumb and foreiinger are placed upon the pivot and springnuts, whilethe latter is pressed toward the former, and thus held until the T restsupon the paper.

In connection with this trigonometer thus constituted may be used, forlaying down or measuring distances on paper, the original scale-plate,patented May 15,1860, the microineter scale, patented June 16, 1863, theimproved drafting-scale, patented February 7, 1865, the scale-dividers,patented February 21, 1871, and some of the other scales now in use,though the last two named are by far the most convenient.

For small work, the sliding T is not required, a rectangulardrafting-board with metallic-adjustable borders being used instead; but,for all large or extended work, it is indispensable. A single metallicbar, one-eighth of an inch thick, one and one-half to two inches wide,and about four feet in length, may be attached to one border of theboard, (depressed for the purpose,) and shifted fromone position toanother as fast as the work on the paper is coinpleted, for an unlimiteddistance; and, if two bars on the opposite borders of the board areused, a breadth of six feet or more may be conveniently given to thepaper; while, by the arrangement above shown for shifting thc Apositionof the graduated limb, any desired side of the drawing may be madeparallel or at right angles with the board. Thus all angles toa minuteof a degree, and all distances to the thousandth of an inch, may be laiddown or measured; and this may be done even more conveniently with thesliding T than with the drafting-board referred to above, having anadjustable metallic border.

I claim- A The combination, as shown, of a sliding T with thetrigonometer, including the head, spring and connecting-plate, for thepurposes set forth.

Witnesses: JOSIAH LYMAN.

WM. S. TUCKER, ROBERT-TUCKER.

